A Vendor Lock-In is when certain software is developed to be incompatible by design with other software that have similar functionality. It is used to establish a monopoly. And any such function is malicious.
This comment thread is for people to document various implementations of this malicious feature.
I got excited when a few month's ago they announced that Ada & Zangemann was going to be made into an animation film. I did not expect them to deliver so fast!